Solution deposition of Pt contacts suited to proton-conducting ceramics

Abstract

We have developed a simple method for depositing high quality platinum (Pt) metal contacts without the necessity of placing the substrate in vacuum or heating it above 180 °C. This method is particularly beneficial for hydrated oxide ceramics, as it prevents water loss and subsequent conductivity degradation. A mixture of two organic solvents was used: ethylene glycol monoethyl ether (EEE) and acetone. By dispersing the precursor PtCl4 in this mixed non-volatile/volatile solvent, homogeneous drying patterns were achieved. EEE was used as the reducing agent, providing a relatively slow rate of Pt deposition, and thereby avoiding formation and subsequent coagulation of Pt clusters. Drop casting of the solution (25 μL/cm2) on mirror-polished surfaces was performed at 25 °C followed by 5 min partial solvent evaporation. The substrate was then heated to 180 °C for ~30 s, resulting in the formation of a metallic Pt layer. The method was successfully tested on 5 mol% Y doped BaZrO3 and 10 mol% Gd doped ceria ceramic pellets, alumina plates, and Kapton ® polymer sheets. The in-plane sheet resistance was 30–110 Ω at room temperature after a single deposition cycle. Because of its versatility and low cost per deposition, the proposed method is very promising for a variety of substrates where high quality electrical contacts prepared at low temperature are required.